1. LiaoNing ShiHua University
Database Principles
LiaoNing ShiHua University

2. Textbooks Required: Recommended: You may also want:
A First Course in Database Systems,2nd, by Jeffrey D.Ullman Jennifer Widom.
Recommended:
王珊,萨师煊. 数据库系统概论(第四版). 高等教育出版社, 2006 年
Books on SQL Server 2000 or 2005
You may also want:
Books on design and programming : Powerbuilder, PowerDesigner, UML, VB, Delphi, VC, JAVA, C#, ASP, PHP, JSP etc.

3. Why Using English Textbook ?
More computer English words
More advanced and newest information
Better information retrieval capability
More international communication chance

4. What to learn in this unit ?
Basic theories (basic)
System and database design (designer)
Application Programming (programmer)
Database management and maintenance (database manager)

5. Syllabus Background and history of database management systems
Fundamentals of using a database management systems: SQL Server2000.
Database modeling
Relational model: theoretical background and operations
Database Language SQL
Fundamentals of database management systems: transactions and security etc.
Database system design and practice

6. Chapter 1 The Worlds of Database Systems
Evolution of Database Systems
Architecture of DBMS and DBS
Future of Database Systems

7. 1.1 Evolution of Database Systems
1.1.1 Some Basic notions
Data
Database (DB)
Database Management System (DBMS)
Database System (DBS).
Database Administrator (DBA)

8. Basic Notions Data Database (DB)
Distinct pieces of information represented in a form suitable for processing by computer.
Data can exist in a variety of forms -- as digital numbers, text, image, sound, video and etc.
Database (DB)
In essence, it’s nothing more than a collection of information that exists over a long period of time.
In common parlance, it refers to a collection of data managed by a database management system (DBMS) or just database system (DBS).

9. Example of Data and Database

10. Another example: University Database
Students
Sid
Sname
Ssex
Sage
sdept
Tom M 21 Cs
Mary F 20
Jack 18
Smith 19 Ma
Alane 22 Is
Courses
Enrolled
cid
Cname
credit 1
Programming 4 2
English 6 3
Physics
Dbms
sid
cid
grade 4 92 3 88 1 70 85 2 95

11. DBMS Database Management System (DBMS)
A collection of programs that enables you to store, modify, and extract information from a database.
There are many different types of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes.

12. Basic functions of DBMS
Data definition
Allow creating new databases and specify their schema (logical structure of the data), via data definition language (DDL).
Data manipulation
Allow efficient access to the data, such as querying and modifying the data, via query language or data manipulation language (DML).
Operation management of DB
Support the storage of very large amounts of data over a long period of time, assuring data integrity, keeping data secure from accident or unauthorized use. Support concurrent, atomic access to data.
Creation and maintenance of DB
Such as inputting and transferring of Data, DB backup and recovery, performance monitoring, audit and analysis etc.

13. Database System (DBS) Database System (DBS). User Application Systems
DB, DBMS, Development Tools, DB applications, DB Administrator (DBA) and users DB OS
DBMS
Developing Tools
DB applications
User
DBA
Hardware
Operating System
DBMS, Compiling System
Developing Tools
Application Systems
DBMS in Computer System

14. Database Administrator
DBA
Person who is responsible for management and maintenance of DB.
Tasks
Database contents and structures
Storage structure and access methods
Database security and integration
Monitor and improve database performance

15. 1.1.2 History of Data management
File systems
Problems: limited support to definition of data schema, no directly support to DML (Data Manipulate Language), no support to efficient concurrent, secure access etc.
Early DBMS
The first commercial DBMS appeared in the late 1960’s, evolved from file systems.
The early DBMS’s used several data models for describing structure of DB: hierarchical model and network model.
Problems: no support to high-level query languages.

16. History of Data management (cont.）
Relational DBMS
A famous paper by Ted Codd in 1970, “A relational model for large shared data banks” in Comm. ACM.
Data organized as tables called relations.
Unlike the user of early DBS, user of a relational system won’t be concerned with the storage structure, and queries are expressed in a very high-level language (SQL).
Today used in most DBMS's.

17. Relational Model Attributes (column headers) Tuples (rows)
Based on tables, such as:
Attributes
(column headers)
acct #
name
balance
12345
Sally
34567
Sue
285.48 …
Tuples
(rows)

18. Query Languages
Employee
Name
Dept
Department
Manager
SELECT Manager FROM Employee, Department WHERE Employee.name = "Clark Kent” AND Employee.Dept = Department.Dept ;

19. History of Data Model Hierarchical model 60’s 70's 80's 90’s now
abstraction of data features in real world into computer world.
Hierarchical model
60’s
70's
80's
90’s
now
Relational model
Choice for most new applications
Object Bases model
Knowledge Bases model
Network model

20. Relational model or not?
Relational model is good for:
Large amounts of data —> simple operations
Navigate among small number of relations
Difficult Applications for relational model:
VLSI Design (CAD in general)
CASE: Computer-Aided Software Engineering
Graphical Data
Where number of "relations" is large, relationships are complex
Object Data Model
Logic Data Model

21. Other Data Models Object data model Logic data model
Usually find objects via explicit navigation, also query language in some systems
Complex Objects – Nested Structure (pointers or references)
Encapsulation, set of Methods/Access functions
Object Identity
Inheritance – Defining new classes like old classes
Logic data model
Prolog, Datalog
More power than relational

22. The DBMS Marketplace
Relational DBMS companies – Oracle, Sybase – are among the largest software companies in the world.
IBM offers its relational DB2 system. With IMS, a nonrelational system, IBM is by some accounts the largest DBMS vendor in the world.
Microsoft offers SQL-Server, plus Microsoft Access for the cheap DBMS on the desktop, answered by “lite” systems from other competitors.
Relational companies also challenged by “object-oriented DB” companies.
But countered with “object-relational” systems, which retain the relational core while allowing type extension as in OO systems.

23. 1.2 Architecture of DBMS Major components of a DBMS Schema Queries
Data
Metadata
Storage Manager
Query Processor
Transaction
Manager
Schema
Modifications
Queries
Schema (logical structure of the data); Metadata(data of data)

24. Architecture of DBS Three Schema Architecture of DBS
External Schema: user schema or subschema
Defines one view of the data as seen by a specific set of application or end users.
There may be many external schemas in a DB.
Schema: conceptual schema, logical schema
Defines data from perspective systems designer;
Independent of end users & data storage mechanism
There is only one conceptual schema in a DB.
Internal Schema: storage schema
Defines how data is organized, stored and manipulated inside the system.
Totally dependent on particular implementation.
There is only one internal schema in a DB.

25. Three Schema Architecture (cont.)
Application A
External Schema 1
Schema
Internal DB B D E C
External Schema 2
External Schema 3

26. Independence of Data and Program
Logical Independence
Via Reflection of External Schema/Schema
One Schema corresponds to many External schemas; every Ex-Schema has an Ex-Schema/Schema Reflection.
When Schema changes, DBA changes the Ex-Schema/Schema reflections, so application programs needn’t been changed.
Physical Independence
Via Reflection of Schema/Internal Schema
Schema/Internal Schema Reflection is unique.
When Internal Schema changes, DBA changes the Schema/ Internal Schema Reflection, so application programs needn’t been changed.

27. Three Aspects to Studying DBMS's
Modeling and design of databases
Allows exploration of issues before committing to an implementation.
Application programming
SQL: queries and DB operations like update.
Host language and Embedded SQL
DBMS implementation
Storage, query processing, transaction, …